Exhaust for internal-combustion engines.



J. M. UNDERWOOD.

EXHAUST FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED 050. II. I9I3.

1,156,447. Patented Oct. 12, 1915.

t I gvwa'n foc 1 names WW eMlvmwWmmmfwawd I I I I III I Mo we ("IHOT/nua- JOHN M. UNDERWOOD,

or rants, ARKANSAS.

EXHAUST FOR INTERNAL-COMBUSTIONENGINES.

Specification of Letters Patent.

Application filed December 11, 1913. Serial No. 805,967.

To all whom it may concern.

Be it known that I, JOHN M. UNuEnwooo, a citizen of the United States,residing at Paris, in the county of Logan and State of.

I ity of a return of the exhaust products, and

at the same time relieving the vacuum which frequently obtains in theexhaust pipe and pocket of the engine immediately following the closingof the exhaust valve.

To these and other ends, the nature of which will be readily understoodas the invention is hereinafter disclosed, said invention consists inthe improved construction and combination of parts hereinafter fullydescribed, illustrated in the accompanying drawings, and moreparticularly pointed out in the appended claim.

In the accompanying drawings, in which similar characters indicatesimilar parts. Figure 1 is a vertical sectional view taken through theattachment and the pipes leading to and from the attachment. Figs. 2 and3 are sectional views taken on the lines 2-2 and 33 respectively of Fig.1.

When the exhaust valve of an internal combustion engine closes at theend of the exhaust stroke, the pressure tending to drive the exhaustgases out of the exhaust pipe is of course suddenly cut off. During themovement immediately following the closing of the exhaust valve,however, the gases continue to rush through the exhaust pipe because oftheir inertia. Thus a partial vacuum is created at the inner end of theexhaust pipe (or exhaust pocket as it is sometimes called). In case theexhaust valve does not seat properly a small amount of the exhaust gasesmay be drawn back into the cylinder during the first part of the intakestroke.

The structure devised by me for overcoming this difficulty is shown inthe accompanying drawings, consisting of a three-way casing 10 havingone of its openings 11 adapted to be threaded to the exhaust outlet 12of the cylinder, the other two openings being substantially in verticalaxial alinement, and an enlarged portion 13 being threaded to thecasing,to form a continuation of the upper opening 14, while the lower portionof the casing is enlarged, as at 15, w th the lower opening 16 threadedto recelve a valve seat 17, to which, ifdesired, a

pipe 18 may be secured. The enlargem'ent 13 has 1ts outer end threadedto receive the eX-' haust pipe 19.

In each of the enlarged portions 13 and 15 of the attachment, I mountvalves 20 and 21, these being supported in suitable spiders 22-. Thesevalves are adapted to operate by gravity, the valve 20 being adapted toopen when pressure is placed within the casing,

while the valve 21 is adapted to be opened under suction action withinthe casing. The valves are of a weight which will provide for maximumefliciency.

Regarding the operation of the attachment it will now be seen thatduring the exhaust stroke of the engine piston the burnt gases will beforced out under pressure and will escape through the valve 20 to theatmosphere through the pipe 19. At this time the internal pressure inthe casing 10 together with the action of gravity holds the air valve 21closed. When the exhaust valve of the cylinder closes, however, thepressure tending to unseat the valve 20 and drive out the exhaust gaseswill be cut 0E. The inertia of the gases is sufficient to cause theircontinued passage throughthe valve 20 for a moment only. This continuedpassage of the gases after the closing of the exhaust valve of thecylinder results in the production of a partial vacuum in the pipe 12.

Patented Oct. 12 i915.

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This vacuum is relieved by the preseht device sincethe valve 21 liftsunder atmospheric pressure to admit sufiicient fresh cool air in thecasing 10. It is now to be explained that the opening of the air valve21 is accompanied by a closing of the exhaust valve. 20. Thus theexhaust gases present in the pipe 19 when the exhaust valve of thecylinder closes are prevented from finding their way back to thepipe 12.

The attachment may be formed in various ways for convenience inassembling, the preference being that the openings 14 and 15 bepositioned in vertical axial alinement, although this may be varied tosome extent without departing from the invention, the principalessential of which is that the outlet be located above the inlet for theair in order that the valves may operate by gravity and be of a typewhich will function with accuracy and freedom of movement.

Having thus described my invention, what T claim as new is:

The combination with an exhaust pipe of an' internal combustion engineof a casing connected to the pipe, an outwardly opening valve for thecasing controlling the issuance of exhaust gases therefrom, and aninwardly opening valve controlling the admission of air to the casing,said first mentioned valve being adapted to remain open and said secondmentioned valve being adapted to re main closed during the exhauststroke of the engine and While the exhaust valve of the engine is open,said first mentioned valve.

In testimony whereof I hereunto aflix my signature in presence of twoWitnesses.

JOHN M. UNDERVVOOD. \Vitnesses:

\V. G. RILEY, J. C. RILEY.

